Mitt Romney Hasn't Got It Locked Up Yet

NEW YORK (TheStreet) -- The earliest Mitt Romney could clinch the Republican nomination is May 29.

The former Massachusetts governor has crept closer to presumed GOP nominee status on a wave of recent momentum that has catapulted him to a strong delegate lead in the Republican primary, and with likely Tuesday victories in Maryland, Wisconsin and Washington D.C., Romney's inevitability seems increasingly more obvious.

Romney, though, would have to win every single delegate from Tuesday's primaries through to Texas' May 29 primary in order to clinch the necessary 1,144 delegates.

"This is a contest that was put together in a certain way that each state had an election put in place ... that allocated their delegates, and if one person got to 1,144 then they become the nominee," said a Rick Santorum campaign operative. "We haven't seen that happen."

Santorum's campaign, like Newt Gingrich's, has staked its chances to win the nomination on a convention floor fight in August. The campaigns have acknowledged the difficulty of overcoming Romney in the primary race.

Santorum has performed well in Southern and Midwestern states among rural voters and areas with large populations of conservative evangelicals, a group that Romney has failed to gain.

Romney has won in key general election swing states like Florida and Ohio and he's won huge in metropolitan areas, where an eventual Republican candidate must be competitive in order to have a shot at defeating Barack Obama in November.

The Santorum campaign operative said that Tuesday's primary contests aren't a make-or-break moment for the former Pennsylvania senator, but one Republican pollster speaking on background said that moment is likely on April 24.

"If Romney does take Wisconsin, I think Pennsylvania becomes Santorum's last stand," said the pollster. "If he can't win his home state, there's no argument that he can make that he ought to continue; he's done well in the South, but that's about it."